Conventionally, technology for improving the performance on ice (braking performance and turning performance) of studless tires is known (for example, see International Patent Publication No. WO/2010/032606 and Japanese Unexamined Patent Application Publication No. 2008-162298A). The pneumatic tires disclosed in International Patent Publication No. WO/2010/032606 and Japanese Unexamined Patent Application Publication No. 2008-162298A each have tread patterns with a plurality of blocks arranged densely in a honeycomb-shape.
Normally, when the resistance to an external force is increased in a specific direction only by making the shape of the blocks anisotropic, a specific performance of the tire performance tends to be improved. For example, if the resistance to an external force in the tire circumferential direction is increased compared with the resistance to an external force in the other directions, the braking performance on ice is improved. Also, if the resistance to an external force in the tire width direction is increased compared with the resistance to an external force in the other directions, the turning performance on ice is improved.
In the pneumatic tire disclosed in International Patent Publication No. WO/2010/032606, there is no anisotropy in the shape of each of the blocks in either the tire circumferential direction or the tire width direction. Also, in the pneumatic tire disclosed in Japanese Unexamined Patent Application Publication No. 2008-162298A, no anisotropy can be seen in the design of groups of blocks formed from a plurality of blocks, when the tread pattern is viewed as a whole, although the shape of each block has anisotropy in the tire width direction.
Accordingly, in the technologies disclosed in International Patent Publication No. WO/2010/032606 and Japanese Unexamined Patent Application Publication No. 2008-162298A, at least when the tread pattern is viewed as a whole, there is no anisotropy in the design of groups of blocks, so it is not clear whether braking performance and turning performance can be exhibited at a high level.